[Docs] Update Installation section
[Docs] Update Installation section

1. If we are not going to install nodejs or io.js from source, we may
not need to have c++ compiler or libssl-dev package
2. the `build-essential` and `libssl-dev` packages should work on all
the Debian and Ubuntu based GNU/Linux distros
3. Remove useless blank lines

PeterDaveHelloKitchen/nvm,evocateur/nvm,edwmurph/nvm,PeterDaveHelloKitchen/nvm,creationix/nvm,creationix/nvm,evocateur/nvm,edwmurph/nvm,ljharb/nvm,ljharb/nvm,PeterDaveHello/nvm,PeterDaveHello/nvm